Hydraulic brake mechanism

ABSTRACT

1,177,552. Hydrodynamic brake. BORGWARNER CORP 18 May, 1967 [29 June. 1966], No. 23212/67. Heading F2E. A fluid motor 17, driven by a pump 15 supplying, fluid through a line 27, is braked by connecting in its fluid exhaust line 28 a variable restriction, comprising ball and spring 54, 55 and a seat 52, which provides a constant retarding force. Pressure in line 27 is applied also to an inlet port 64 of a valve 19 containing the variable restriction assembly so that the piston 44 is moved to the right until the reduced diameter section 45 connects the inlet port 63 receiving the motor exhaust fluid to an exhaust port 29. The motor 17 is then free to be driven by the inlet fluid at 20 from line 27, and to drive, for example, the cage 10 of a washing machine. Stopping of the pump 15 causes the piston to move to the left, and the motor 17 to be braked as stated, the exhaust fluid then leaving the valve 19 through port 29. Reversal of the pump 15 supplies pressure on line 26 to operate a locking device 18 to prevent any rotation of the motor 17, and also drives a further member 16 which may be the agitator of the washing machine.

' Jan. 30, 1968 H. N. UNDERWOOD HYDRAULIC BRAKE MECHANISM Filed June 29, 1966 fnl/67?. 07" 4 rerNZZnderwood United States Patent O 3,365,887 HYDRAULIC BRAKE MECHANISM Herbert N. Underwood, Chicago, Ill., assignor to Borg- Warner Corporation, Chicago, lll., a corporation of Illinois Filed .lune 29, 1966, Ser. No. 561,436 3 Claims. (Cl. 60--53) ABSTRACT F THE DISCLOSURE The invention consists of a brake mechanism for the iiuid motor drive of a clothes basket in a clothes washer, the brake mechanism comprising a valve controlling the luid exhaust of the motor such that when the uid ow to the motor is interrupted, the valve moves from a position providing a free exhaust to a position providing a variable restriction to the flow of exhaust Huid.

This invention relates to a hydraulic transmission. More particularly, this invention relates to a hydraulic transmission including an improved brake mechanism for an automatic clothes washer although use in other machines is contemplated.

It is an object of this invention to provide an improved brake mechanism for the clothes basket of an automatic washing machine wherein after the spin cycle is interrupted the clothes basket may be quickly brought to a stop.

It is a further object to provide an improved brake mechanism for an automatic clothes washer drive incorporating a uid motor to drive the clothes basket wherein when the spin cycle is interrupted the brake mechanism will automatically restrict the uid exhaust from the fluid motor thereby bringing the clothes basket to a stop in minimum time. The mechanism providing the braking of the clothes basket includes a variable restricting orice designed so as to maintain a constant iluid pressure in the fluid exhaust from the motor to provide an improved brake of the clothes basket as compared to known structures in the prior art.

The invention consists of the novel constructions, arrangements and devices to be hereinafter described and claimed for carrying out the above-stated objects and such other objects as will appear from the following description of the preferred embodiment of an invention illustrated with reference to the accompanying drawings wherein a schematic diagram of a hydraulic transmission incorporating the principles of the invention is illustrated.

Referring to the drawing, a hydraulic transmission is illustrated which is operable in connection with a clothes basket and agitator 11 of a washing machine. The transmission 12 includes a reversible fluid pump 15, a uid motor 16 adapted to drive the agitator 11, a fluid motor 17 connected to the spin basket 10 and adapted to rotate the spin basket, a basket lock mechanism 18 and a brake valve 19.

Fluid motor 17 includes an inlet port 20 and an outlet port 21 each schematically illustrated in the drawing. The motor 17 includes an internal gear rotary element 23 and an external gear rotary element 24 mounted within element 23. Element 24 is drivingly connected to a sleeve 25 which in turn is drivingly connected to the clothes basket 10.

A lluid conduit 26 interconnects Huid pump 15, agitator motor 16 and basket lock mechanism 18. A uid conduit 27 interconnects lluid pump 15, inlet port 20 of spin motor 17 and brake valve 19. A fluid conduit 28 connects the output port 21 of the fluid motor 17 to the brake valve 19. A iiuid sump 29 is schematically illustrated for the hydraulic transmission.

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This invention, relating to the brake valve mechanism 19, comprises an improvement over the structure disclosed in copending application Ser. No. 513,206 of common assignee to which reference may be had for a more complete description of the pump and agitator motor mechanisms.

As described in the above mentioned application, the fluid pump 15 is adapted to be rotated in two directions of rotation. When the iluid pump is rotated in a direction to supply pressure to conduit 26 the agitator motor 16 will be actuated to drive agitator 11. At the same time the fluid pressure in conduit 26 actuates basket lock mechanism 1S to hold the rotary element 23 of the spin motor 17 and since outer element 23 holds the inner element 24 which is connected to the spin basket 10, the brake mechanism 18 thus holds clothes basket 11i stationary during the agitate cycle as is necessary in washing machines. When the pump 15 is reversed uid pressure is then supplied into conduit 27 which iiows to the input port 20 of the spin motor 17 to thereby rotate the spin motor 17 and drive the clothes basket 1?. At this time there is no uid pressure in conduit 26 so that the brake mechanism 18 is withdrawn allowing the clothes basket to be spun. Fluid pressure in conduit 27 is also supplied to the brake valve 19.

The brake valve 19 includes a Valve body 40 having a bore 41 therein. Slidable within bore l1 is a valve spool 42. The valve spool 42 has lands 43 and 44. A groove 45 separates lands 44 and 43. A hollow cavity 4S is provided in land 43. A shallow groove 50 is also provided within land 43. Cavity 48 within land 43 is connected to groove 50 by means of a uid passage 51. Also provided in the cavity 48 is a valve seat 52 surrounding a port 53 connected to passage 51. A ball 54 is provided engageable with seat 52. The ball 54 is urged into engagement with seat 52 by spring 55.

An exhaust port 57 is provided in one end of land 43 and is connected to cavity 48.

A spring 60 is mounted within the bore 41 and engages the valve spool 42 urging the valve spool 42 to the left as viewed in the drawing.

The brake valve body 40 includes ports 63, 64, 65 and 66. Port 64 is connected to receive fluid pressure from conduit 27 during the spin cycle of the wash machine. Fluid port 63 is connected to conduit 2S and thereby to the exhaust port 21 of the spin motor 17. Ports 65 and 66 are each exhaust ports connected to the fluid sump 29. The function of the improved brake valve 19 is as follows: when the washing machine is in the spin cycle as described above, Huid pressure is supplied to conduit 27 and inlet port 20 of motor 17 to operate iiuid motor 17 and rotate the clothes basket 10. Fluid pressure will also be supplied through port 64 of brake valve 19 and will move the valve spool 42 to the right in which position ports 63 and 65 are interconnected by large groove 45. Thus the spin motor is connected to the sump through the brake valve 19 allowing the spin motor 17 to operate in a desired manner to rotate the clothes basket 10. When the spin cycle is interrupted and pressure no longer exists in fluid conduit 27 and before pressure is supplied to conduit 26, the valve spool 42 will be moved to the left to the position illustrated in the drawing by spring 60. In this position exhaust fluid pressure from motor 17 in conduit 28 is connected through port 63 and groove 5t) to fluid passage 51. If this pressure exceeds the setting of ball 54 and spring 55, the ball 54 will move oif the seat 52 and allow fluid pressure to ilow to the sump through port 66 in a restricted manner. Thus lluid ilow is impeded through exhaust conduit 28 so that the spin motor 17 will act as a dynamic fluid brake to bring the clothes basket to a stop.

In the copending application mentioned above a xed orifice was provided for the braking mechanism to bring the clothes basket to a stop. In the improved structure of brake value 19 a variable orifice or restriction constituting the valve seat 52 and ball 54 is provided. Due to the action of ball 54 and spring S5 the brake valve 19 tends to maintain a constant fluid pressure within exhaust conduit 28 thereby bringing the clothes basket to a stop as quickly as possible. With a xcd orifice structure as in the above mentioned application, as the ow across the oritice decreases near the end of the stop cycle the pressure in the exhaust conduit 28 would also tend to decrease thereby decreasing the braking effect of the spin motor 17. In the improved structure of the present valve mechanism, the ball 54 will `tend to move against seat 52 and reduce the orifice size when the pressure in conduit 28 drops and tlow -through the orifice decreases. Thus the ball 54 by decreasing the size of the orice will tend to raise pressure in conduit 28 and maintain a constant pressure over the duration of the spin brake cycle.

Thus it will be apparent that an improved brake mechanism for a hydraulic washing machine has been provided in that the time required to stop the clothes basket of the washing machine has been reduced and that, by the addition of a variable orifice to the known brake valve mentioned in the above application a fairly simple and economical method has been provided of maintaining a constant braking uid pressure in the exhaust conduit from the spin motor so that the braking eifect of the spin motor is maintained throughout a greater extent of the spin brake cycle than has been possible in known prior art structures.

Further, the variable restriction or orice of the present invention has been built within the valve spool of the above described known valve thereby making unnecessary extensive modication of the valve body in which the invention is utilized.

Various of the features of the invention have been particularly shown and described; however, it should be obvious to one skilled in the art that various modifications may be made therein without departing from the scope of the invention.

What is claimed is:

1. In a hydraulic transmission, a uid pump, a fluid motor and an output member, a fluid circuit interconnecting said fluid motor and said pump, said fluid motor being adapted to rotate said output member when receiving uid pressure from said pump7 a valve connected to said circuit, means to exhaust uid from said motor, said valve also being connected to said means, a variable uid restriction within said valve connectible with said exhaust means, said valve including a spool which moves in response to pressure in said circuit to a position providing an unrestricted outlet for iluid from said exhaust means, and said variable fluid restriction comprising a seat, a ball engageable with said seat, and a spring, all contained within said spool, said spring urging said ball into engagement with said seat whereby said restriction will tend to maintain constant pressure in said exhaust means, whereby when said motor is no longer receiving fluid pressure from said pump said valve will variably restrict said exhaust means to retard rotation of said motor and thereby act as a brake for said output member.

2. A transmission as claimed in claim 1, said valve having a pressure inlet port connected to said exhaust means and a fluid exhaust port, said valve spool having a groove adapted to provide unrestricted uid communication between said inlet and exhaust ports.

3. A transmission as claimed in claim 2, said valve having a cavity therein, an inlet connecting fluid ypressure from said pressure inlet into said cavity when said spool is in the position as urged by said spring, a variable restriction in said cavity restricting flow into said cavity whereby a restricted communication is provided between said pressure inlet and Huid exhaust ports.

References Cited UNITED STATES PATENTS 2,489,411 11/1949 Harringgon 244-103 2,599,450 6/1952 Henning 60-53 2,632,301 3/1953 Brodie 60-53 2,759,684 8/1956 Cross 242-90 2,975,803 3/1961 Vallee 137-5992 2,980,193 4/1961 Baudhuin et al 60-53 X 3,153,900 10/1964 Plgeroulet et al 60-53 X 3,242,703 3/1966 Brundage 68-23 FOREIGN PATENTS 746,350 3/1933 France.

MARTIN P. SCHWADRON, Primary Examiner.

G. N. BAUM, Assistant Examiner. 

